Schizophrenia, clinical anxiety and depression daily affect many millions of people. These conditions are brain disorders that have serious and lasting effects on people's lives and impact the sufferers and their friends and relatives.
People with schizophrenia often have trouble thinking clearly or making decisions. They may have a hard time telling real life from fantasy. They may have so-called positive symptoms such as delusions or hallucinations which they experience but which do not reflect reality, and see or believe things that are not real; or they may have negative symptoms and lack behaviors or feelings that normal people have, avoid social contact and be emotionally withdrawn. Often they start to do things, but not follow through and take no pleasure or interest in life; they may be confused in thinking and speech and act in ways that do not make sense.
People who have generalized anxiety disorder (GAD) worry excessively and uncontrollably about everyday things. This constant worry affects daily functioning and physical symptoms can include sweating, nausea, gastrointestinal discomfort or diarrhea. Sufferers tend to be irritable and complain about feeling on edge, are easily tired and have trouble sleeping. GAD can occur with other anxiety disorders, depressive disorders, or substance abuse. The intensity, duration and frequency of worrying varies but is disproportionate to the issue and interferes with the sufferer's performance of tasks and ability to concentrate.
Depressive disorder is an illness that involves the body, mood, and thoughts. It affects the way a person eats and sleeps, the way they feel about themselves, and the way they think about things. People with a depressive illness cannot merely “pull themselves together” and get better. Without treatment, symptoms can last for weeks, months, and even years. Major depression interferes with a person's ability to work, study, sleep, eat, and enjoy life. A disabling episode of depression may occur only once but more commonly occurs several times in a lifetime. A less severe type of depression, termed dysthymia, involves long-term, chronic symptoms that do not disable, but keep one from functioning well or from feeling good. Many people with dysthymia also experience major depressive episodes at some time in their lives. Bipolar disorder is yet another type of depression that is also called manic-depressive illness. It is not as prevalent as other forms of depressive disorders and bipolar disorder is characterized by cycling mood changes that swing between manic highs and depressive lows. Sometimes the mood switches are dramatic and rapid, but most often they are gradual. When in the depressed phase, a person can have any or all of the symptoms of a depressive disorder. When in the manic phase, a person may be overactive, overtalkative, and have a great deal of energy. Manic persons often think differently and their judgment and social behavior changes in ways that cause serious problems and embarrassment; they may feel elated, have grand schemes, make unwise business decisions and indulge in romantic sprees. Untreated mania can also evolve into a psychotic state.
Schizophrenia, clinical anxiety and depression are brain disorders thought to arise from the overactivity, underactivity or imbalanced activity of brain cells. Activities of brain cells and all thinking and feeling are thought to result from the activities of different brain messengers interacting with receptors on brain cells. Acetylcholine is one of several messengers by which brain cell communicate with each other. Acetylcholine interacts with numerous kinds of receptors some of which are the nicotinic acetylcholine receptors that are susceptible to the actions of nicotine found in tobacco. The use of compounds which bind nicotinic acetylcholine receptors in the treatment of a range of disorders including schizophrenia, anxiety and depression, Alzheimer's disease, cognitive or attention disorders, Tourette's syndrome, and Parkinson's disease has been discussed in McDonald et al. (1995) “Nicotinic Acetylcholine Receptors: Molecular Biology, Chemistry and Pharmacology”, Chapter 5 in Annual Reports in Medicinal Chemistry, vol. 30, pp. 41-50, Academic Press Inc., San Diego, Calif.; and in Williams et al. (1994) “Neuronal Nicotinic Acetylcholine Receptors,” Drug News & Perspectives, vol. 7, pp. 205-223.
Various nicotinic acetylcholine receptors are known, but one of particular interest is the alpha-7 nicotinic acetylcholine receptor and compounds targeting the alpha-7 receptor are thought to be particularly beneficial for treating schizophrenia, anxiety and depression.